Intracanopy adjustment of leaf-level thermal tolerance is associated with microclimatic variation across the canopy of a desert tree (Acacia papyrocarpa).

Tree crowns are spatially heterogeneous, sometimes resulting in significant variation in microclimate across the canopy, particularly with respect to temperature. Yet it is not known whether such localised temperature variation equates to intracanopy variation in leaf-level physiological thermal tolerance. Here, we studied whether microclimate variation across the canopy of a dominant desert tree equated to localised variation in leaf thermal thresholds (T50) among four canopy positions: upper south, upper north, lower south, lower north. Principal component analysis was used to generate a composite climatic stress variable (CSTRESS) from canopy temperature, vapour pressure deficit, and relative humidity. We also determined the average number of days that maximum temperatures exceeded the air temperature equating to this species' critical threshold of 49 °C (AT49). To estimate how closely leaf temperatures track ambient temperature, we predicted the thermal time constant (τ) for leaves at each canopy position. We found that CSTRESS and AT49 were significantly greater in lower and north-facing positions in the canopy. Differences in wind speed with height resulted in significantly longer predicted τ for leaves positioned at lower, north-facing positions. Variation in these drivers was correlated with significantly higher T50 for leaves in these more environmentally stressful canopy positions. Our findings suggest that this species may optimise resources to protect against thermal damage at a whole-plant level. They also indicate that, particularly in desert environments with steep intracanopy microclimatic gradients, whole-plant carbon models could substantially under- or overestimate productivity under heat stress, depending on where in the canopy T50 is measured.

Routine use of fluoroscopic guidance and up-front femoral angiography results in reduced femoral complications in patients undergoing coronary angiographic procedures: an observational study using an Interrupted Time-Series analysis.

Transradial access is increasingly used for coronary angiography and percutaneous coronary intervention, however, femoral access remains necessary for numerous procedures, including complex high-risk interventions, structural procedures, and procedures involving mechanical circulatory support. Optimising the safety of this approach is crucial to minimize costly and potentially life-threatening complications. We initiated a quality improvement project recommending routine fluoroscopic guidance (femoral head), and upfront femoral angiography should be performed to assess for location and immediate complications. We assessed the effect of these measures on the rate of vascular complications. Data were collected prospectively on 4534 consecutive patients undergoing femoral coronary angiographic procedures from 2015 to 2017. The primary end-point was any access complication. Outcomes were compared pre and post introduction including the use of an Interrupted Time-Series (ITS) analysis. 1890 patients underwent angiography prior to the introduction of routine fluoroscopy and upfront femoral angiography and 2644 post. All operators adopted these approaches. Baseline characteristics, including large sheath use, anticoagulant use and PCI rates were similar between the 2 groups. Fluoroscopy-enabled punctures were made in the 'safe zone' in over 91% of cases and upfront femoral angiography resulted in management changes i.e. procedural abandonment prior to heparin administration in 21 patients (1.1%). ITS analysis demonstrated evidence of a reduction in femoral complication rates after the introduction of the intervention, which was over and above the existing trend before the introduction (40% decrease RR 0.58; 95% CI: 0.25-0.87; P < 0.01). Overall these quality improvement measures were associated with a significantly lower incidence of access site complications (0.9% vs. 2.0%, P < 0.001). Routine fluoroscopy guided vascular access and upfront femoral angiography prior to anticoagulation leads to lower vascular complication rates. Thus, study shows that femoral intervention can be performed safely with very low access-related complication rates when fluoroscopic guidance and upfront angiography is used to obtain femoral arterial access.

A randomized double-blind control study of early intra-coronary autologous bone marrow cell infusion in acute myocardial infarction: the REGENERATE-AMI clinical trial†.

AIMS: Clinical trials suggest that intracoronary delivery of autologous bone marrow-derived cells (BMCs) 1-7 days post-acute myocardial infarction (AMI) may improve left ventricular (LV) function. Earlier time points have not been evaluated. We sought to determine the effect of intracoronary autologous BMC on LV function when delivered within 24 h of successful reperfusion therapy. METHODS AND RESULTS: A multi-centre phase II randomized, double-blind, and placebo-controlled trial. One hundred patients with anterior AMI and significant regional wall motion abnormality were randomized to receive either intracoronary infusion of BMC or placebo (1:1) within 24 h of successful primary percutaneous intervention (PPCI). The primary endpoint was the change in left ventricular ejection fraction (LVEF) between baseline and 1 year as determined by advanced cardiac imaging. At 1 year, although LVEF increased compared with baseline in both groups, the between-group difference favouring BMC was small (2.2%; 95% confidence interval, CI: -0.5 to 5.0; P = 0.10). However, there was a significantly greater myocardial salvage index in the BMC-treated group compared with placebo (0.1%; 95% CI: 0.0-0.20; P = 0.048). Major adverse events were rare in both treatment groups. CONCLUSION: The early infusion of intracoronary BMC following PPCI for patients with AMI and regional wall motion abnormality leads to a small non-significant improvement in LVEF when compared with placebo; however, it may play an important role in infarct remodelling and myocardial salvage.

Randomized trial of combination cytokine and adult autologous bone marrow progenitor cell administration in patients with non-ischaemic dilated cardiomyopathy: the REGENERATE-DCM clinical trial.

AIMS: The REGENERATE-DCM trial is the first phase II randomized, placebo-controlled trial aiming to assess if granulocyte colony-stimulating factor (G-CSF) administration with or without adjunctive intracoronary (IC) delivery of autologous bone marrow-derived cells (BMCs) improves global left ventricular (LV) function in patients with dilated cardiomyopathy (DCM) and significant cardiac dysfunction. METHODS AND RESULTS: Sixty patients with DCM and left ventricular ejection fraction (LVEF) at referral of ≤45%, New York Heart Association (NYHA) classification ≥2 and no secondary cause for the cardiomyopathy were randomized equally into four groups: peripheral placebo (saline), peripheral G-CSF, peripheral G-CSF and IC serum, and peripheral G-CSF and IC BMC. All patients, except the peripheral placebo group, received 5 days of G-CSF. In the IC groups, this was followed by bone marrow harvest and IC infusion of cells or serum on Day 6. The primary endpoint was LVEF change from baseline to 3 months, determined by advanced cardiac imaging. At 3 months, peripheral G-CSF combined with IC BMC therapy was associated with a 5.37% point increase in LVEF (38.30% ± 12.97 from 32.93% ± 16.46 P = 0.0138), which was maintained to 1 year. This was associated with a decrease in NYHA classification, reduced NT-pro BNP, and improved exercise capacity and quality of life. No significant change in LVEF was seen in the remaining treatment groups. CONCLUSION: This is the first randomized, placebo-controlled trial with a novel combination of G-CSF and IC cell therapy that demonstrates an improvement in cardiac function, symptoms, and biochemical parameters in patients with DCM.

Central iliac arteriovenous anastomosis for hypertension: targeting mechanical aspects of the circulation.

Raised blood pressure is the leading attributable risk factor for global morbidity and mortality. Real world data demonstrates that half of treated patients are at elevated cardiovascular risk because of inadequately controlled BP. In addition to pharmacotherapy, certain interventional strategies to reduce blood pressure and cardiovascular risk in hypertension can be considered according to international guidelines. One of the newer technologies entering this field is a proprietary arteriovenous coupler device that forms a fixed flow arteriovenous conduit in the central vasculature. In this review, we examine the development of and rationale for the creation of a central arteriovenous anastomosis in patients with hypertension and review the proposed mechanisms by which it may ameliorate hypertension. We critically review the clinical trial evidence base to date and postulate on future therapeutic directions.

Reconstructing relative genome size of vascular plants through geological time.

The strong positive relationship evident between cell and genome size in both animals and plants forms the basis of using the size of stomatal guard cells as a proxy to track changes in plant genome size through geological time. We report for the first time a taxonomic fine-scale investigation into changes in stomatal guard-cell length and use these data to infer changes in genome size through the evolutionary history of land plants. Our data suggest that many of the earliest land plants had exceptionally large genome sizes and that a predicted overall trend of increasing genome size within individual lineages through geological time is not supported. However, maximum genome size steadily increases from the Mississippian (c. 360 million yr ago (Ma)) to the present. We hypothesise that the functional relationship between stomatal size, genome size and atmospheric CO2 may contribute to the dichotomy reported between preferential extinction of neopolyploids and the prevalence of palaeopolyploidy observed in DNA sequence data of extant vascular plants.

A comparative analysis of photosynthetic recovery from thermal stress: a desert plant case study.

Our understanding of the effects of heat stress on plant photosynthesis has progressed rapidly in recent years through the use of chlorophyll a fluorescence techniques. These methods frequently involve the treatment of leaves for several hours in dark conditions to estimate declines in maximum quantum yield of photsystem II (F(V)/F(M)), rarely accounting for the recovery of effective quantum yield (ΔF/F(M')) after thermally induced damage occurs. Exposure to high temperature extremes, however, can occur over minutes, rather than hours, and recent studies suggest that light influences damage recovery. Also, the current focus on agriculturally important crops may lead to assumptions about average stress responses and a poor understanding about the variation among species' thermal tolerance. We present a chlorophyll a fluorescence protocol incorporating subsaturating light to address whether species' thermal tolerance thresholds (T 50) are related to the ability to recover from short-term heat stress in 41 Australian desert species. We found that damage incurred by 15-min thermal stress events was most strongly negatively correlated with the capacity of species to recover after a stress event of 50 °C in summer. Phylogenetically independent contrast analyses revealed that basal divergences partially explain this relationship. Although T 50 and recovery capacity were positively correlated, the relationship was weaker for species with high T 50 values (>51 °C). Results highlight that, even within a single desert biome, species vary widely in their physiological response to high temperature stress and recovery metrics provide more comprehensive information than damage metrics alone.

Clinical outcomes after myocardial revascularization according to operator training status: cohort study of 22,697 patients undergoing percutaneous coronary intervention or coronary artery bypass graft surgery.

AIMS: Myocardial revascularization by either coronary artery bypass graft surgery (CABG) or percutaneous coronary intervention (PCI) carries the risk of serious complications. Observational data suggest that outcomes may be improved by experienced operators, but there are few studies that have analysed the relationship between mortality and primary operator grade. The aim of this study was to investigate the effect of operator grade (trainee vs. consultant) upon outcomes of revascularization procedures. METHODS AND RESULTS: This was an observational study at a tertiary cardiology centre with accredited training programmes, between 2003 and 2011. A total of 22 697 consecutive patients undergoing either CABG or PCI were included. Associations between operator grade and mortality were assessed by hazard ratios, estimated by Cox regression analyses; 6689 patients underwent CABG, whereas 16 008 underwent PCI. Trainees performed 1968 (29.4%) CABG procedures and 8502 (53.1%) PCI procedures. The proportion of procedures performed by trainees declined over time for both CABG (30.2% in 2003 vs. 26.0% in 2010) and for PCI (58.1% in 2003 vs. 44.5% in 2010). In the unadjusted Cox analysis, consultant operator grade was associated with an increased 5-year mortality after both CABG [HR: 1.26 (95% CI: 1.07-1.47)] and PCI procedures [HR: 1.34 (95% CI: 1.22-1.47)] compared with a trainee operator. However, following multiple adjustment, consultant grade was no longer associated with mortality after either procedure [CABG: HR: 1.02 (95% CI: 0.87-1.20), PCI: HR: 1.08 (95% CI: 0.98-1.20)]. CONCLUSION: There was no observed detrimental effect on patient outcomes arising from procedures undertaken by trainees working in a structured training environment compared with consultants.

Deployment of drug-eluting stents for isolated proximal lad disease is associated with lower major adverse cardiac events and no increase in stent thrombosis when compared with bare metal stents: a 5-year observational cohort study.

BACKGROUND: Drug-eluting stents (DES) may be associated with an increased risk of late stent thrombosis (ST) compared with bare metal stents (BMS). We compared major adverse cardiac events (MACE) and long term all cause mortality in patients with isolated proximal LAD disease treated with DES or BMS. METHOD AND RESULTS: This study of 1653 patients with isolated proximal LAD disease, includes 643 treated with BMS and 1010 treated with DES. All patients received standard dual antiplatelet treatment. MACE after 5 years were less frequent in DES compared with BMS (12.1% 95% CI 9.3-14.2 versus 21.3% 95% CI: 16.9-25.1, P < 0.0001), driven largely by a decreased rate of both target vessel and lesion revascularization (TVR: 6.3%, 95% CI 4.0-7.5% versus 14.7%, 95% CI 11.0-17.3%, P < 0.0001, TLR: (5.3%, 95% CI 3.2-7.1% versus 13.2%, 95% CI 9.8.0-15.4%, P < 0.0001). There was no difference in the rate of death, myocardial infarction, or CVA. Incidence of stent thrombosis was also comparable (1.2% 95% CI: 0.6-2.6% versus 1.1% 95% CI: 0.6-2.5%, P = 0.8). Adjusted Cox analysis confirmed a decreased risk of MACE for DES compared with BMS 0.55 (95% confidence intervals 0.41-0.73) with no difference in the hazard of all cause mortality (HR: 1.04 95% CI: 0.67-1.61). CONCLUSION: When treating proximal LAD disease, use of DES was associated with a lower MACE rate than BMS, with no differences in the incidence of stent thrombosis, myocardial infarction or 5 year all cause mortality. Our data suggests that despite the adverse prognostic correlates of proximal LAD disease, DES deployment in this location is both safe and clinically more effective than BMS.

An Observational Study Assessing the Predictors of Procedural Failure From the Radial Approach: Is Right Radial Access Always the Best?

OBJECTIVE: The study aimed to determine the predictors of procedural failure (coronary cannulation) in patients undergoing coronary angiography ± percutaneous coronary intervention (PCI) from the transradial (TR) approach. METHODS: We conducted an observational study of 20,315 consecutive patients undergoing TR angiography between 2016 and 2020. TR failure was described as inability to cannulate the coronary arteries. Univariate and multivariate analyses were performed to determine independent predictors of TR failure. RESULTS: Out of the study population, TR failure was observed in 365 (1.8%) patients, out of which 281 (77%) crossed over successfully to the transfemoral (TF) route and 84 (23%) to left radial access (LRA). Unsuccessful procedures were most likely seen in patients who were elderly, female, BAME background, short stature or with a history of hypertension, diabetes, and renal disease. On regression analysis, age (OR: 1.024; 95% Cl: 1.014-1.035), female gender (OR: 0.729; 95% Cl: 0.555-0.957), BAME (OR: 0.786; 95% Cl: 0.612-0.959), height (OR: 0.988; 95% Cl: 0.977-0.999), hypertension (OR: 1.510; 95% Cl: 1.147-1.987) and RRA (OR: 1.977; 95% Cl: 1.105-3.538) were independent predictors of TR failure. On further analysis, these predictors of failure were not seen from the LRA approach. CONCLUSION: This study identifies that rates of TR failure are low and that predictors of failure differ between the RRA and LRA. The difference in predictors between the 2 routes suggests that in patients when coronary cannulation is unsuccessful via the RRA then the LRA could be considered as a second access site. Further study is needed to see if in selected patient groups the LRA could be used as the first-choice access route.

Almanac 2011: acute coronary syndromes. The national society journals present selected research that has driven recent advances in clinical cardiology.

This overview highlights some recent advances in the epidemiology, diagnosis, risk stratification and treatment of acute coronary syndromes. The sheer volume of new studies reflects the robust state of global cardiovascular research but the focus here is on findings that are of most interest to the practising cardiologist. Incidence and mortality rates for myocardial infarction are in decline, probably owing to a combination of lifestyle changes, particularly smoking cessation, and improved pharmacological and interventional treatment. Troponins remain central for diagnosis and new high-sensitivity assays are further lowering detection thresholds and improving outcomes. The incremental diagnostic value of other circulating biomarkers remains unclear and for risk stratification simple clinical algorithms such as the GRACE score have proved more useful. Primary PCI with minimal treatment delay is the most effective reperfusion strategy in ST elevation myocardial infarction (STEMI). Radial access is associated with less bleeding than with the femoral approach, but outcomes appear similar. Manual thrombectomy limits distal embolisation and infarct size while drug-eluting stents reduce the need for further revascularisation procedures. Non-culprit disease is best dealt with electively as a staged procedure after primary PCI has been completed. The development of antithrombotic and antiplatelet regimens for primary PCI continues to evolve, with new indications for fondaparinux and bivalirudin as well as small-molecule glycoprotein (GP)IIb/IIIa inhibitors. If timely primary PCI is unavailable, fibrinolytic treatment remains an option but a strategy of early angiographic assessment is recommended for all patients. Non-ST segment elevation myocardial infarction(NSTEMI) is now the dominant phenotype and out-comes after the acute phase are significantly worse than for STEMI. Many patients with NSTEMI remain undertreated and there is a large body of recent work seeking to define the most effective antithrombotic and antiplatelet regimens for this group of patients.The benefits of early invasive treatment for most patients are not in dispute but optimal timing remains unresolved. Cardiac rehabilitation is recommended for all patients with acute myocardial infarction but take-up rates are disappointing. Home-based programmes are effective and may be more acceptable for many patients. Evidence for the benefits of lifestyle modification and pharmacotherapy for secondary prevention continues to accumulate but the argument for omega-3 fatty acid supplements is now hard to sustain following recent negative trials. Implantable cardioverter defibrillators for patients with severe myocardial infarction protect against sudden death but for pri-mary prevention should be based on left ventricular ejection fraction measurements late (around 40 days)after presentation, earlier deployment showing no mortality benefit.

Investigating consultant-led virtual review as a model for implementing 7-day cardiology services in UK clinical practice.

BACKGROUND: Disparities between weekend and weekday care, termed 'the weekend effect', have led to a UK government pledge to provide 7-day services. Despite this, poor outcomes have led to criticism of the programme. This study consequently sought to evaluate consultant-led virtual review as a model for 7-day cardiology services. METHODS: Over 4 weekends, cardiology patients underwent virtual review alongside in-person teams. Outcomes included length of stay, same-day discharge and 30-day mortality rates, as well as duration of ward rounds and change in patient management. Patients were surveyed on attitudes towards virtual review. RESULTS: Statistical analysis revealed no significant difference in clinical outcomes, while virtual review was noted to significantly decrease time taken (p<0.0001). Attitudes towards virtual review were broadly favourable. CONCLUSION: By demonstrating comparable outcomes compared with conventional review, as well as high acceptability, this study identified virtual review as an effective substitute for in-person care.

Validation of the CREST score for predicting circulatory-aetiology death in out-of-hospital cardiac arrest without STEMI.

AIMS: The CREST tool was recently developed to stratify the risk of circulatory-aetiology death (CED) in out-of-hospital cardiac arrest (OHCA) patients without ST-elevation myocardial infarction (STEMI). We aimed to validate the CREST score using an external cohort and determine whether it could be improved by the addition of serum lactate on admission. METHODS: The study involved the retrospective analysis of consecutive patients admitted to a single tertiary centre with OHCA of presumed cardiac origin over a 51-month period. The CREST score was calculated by attributing points to the following variables: Coronary artery disease (CAD), non-shockable Rhythm, Ejection fraction <30%, cardiogenic Shock at presentation and ischaemic Time ≥25 minutes. The primary endpoint was CED vs neurological aetiology death (NED) or survival. RESULTS: Of 500 patients admitted with OHCA, 211 did not meet criteria for STEMI and were included. 115 patients died in hospital (71 NED, 44 CED). When analysed individually, CED was associated with all CREST variables other than a previous diagnosis of CAD. The CREST score accurately predicted CED with excellent discrimination (C-statistic 0.880, 95% CI 0.813-0.946) and calibration (Hosmer and Lemeshow P=0.948). Although an admission lactate ≥7 mmol/L also predicted CED, its addition to the CREST score (the C-AREST score) did not significantly improve the predictive ability (CS 0.885, 0.815-0.954, HS P=0.942, X2 difference in -2 log likelihood =0.326, P=0.850). CONCLUSION: Our study is the first to independently validate the CREST score for predicting CED in patients presenting with OHCA without STEMI. Addition of lactate on admission did not improve its predictive ability.

The use of novel oral anticoagulants compared to vitamin K antagonists (warfarin) in patients with left ventricular thrombus after acute myocardial infarction.

AIM: Current guidelines recommend the use of vitamin K antagonist (VKA) for up to 3-6 months for treatment of left ventricular (LV) thrombus post-acute myocardial infarction (AMI). However, based on evidence supporting non-inferiority of novel oral anticoagulants (NOAC) compared to VKA for other indications such as deep vein thrombosis, pulmonary embolism (PE), and thromboembolic prevention in atrial fibrillation, NOACs are being increasingly used off licence for the treatment of LV thrombus post-AMI. In this study, we investigated the safety and effect of NOACs compared to VKA on LV thrombus resolution in patients presenting with AMI. METHODS AND RESULTS: This was an observational study of 2328 consecutive patients undergoing coronary angiography ± percutaneous coronary intervention (PCI) for AMI between May 2015 and December 2018, at a UK cardiac centre. Patients' details were collected from the hospital electronic database. The primary endpoint was rate of LV thrombus resolution with bleeding rates a secondary outcome. Left ventricular thrombus was diagnosed in 101 (4.3%) patients. Sixty patients (59.4%) were started on VKA and 41 patients (40.6%) on NOAC therapy (rivaroxaban: 58.5%, apixaban: 36.5%, and edoxaban: 5.0%). Both groups were well matched in terms of baseline characteristics including age, previous cardiac history (previous myocardial infarction, PCI, coronary artery bypass grafting), and cardiovascular risk factors (hypertension, diabetes, hypercholesterolaemia). Over the follow-up period (median 2.2 years), overall rates of LV thrombus resolution were 86.1%. There was greater and earlier LV thrombus resolution in the NOAC group compared to patients treated with warfarin (82% vs. 64.4%, P = 0.0018, at 1 year), which persisted after adjusting for baseline variables (odds ratio 1.8, 95% confidence interval 1.2-2.9). Major bleeding events during the follow-up period were lower in the NOAC group, compared with VKA group (0% vs. 6.7%, P = 0.030) with no difference in rates of systemic thromboembolism (5% vs. 2.4%, P = 0.388). CONCLUSION: These data suggest improved thrombus resolution in post-acute coronary syndrome (ACS) LV thrombosis in patients treated with NOACs compared to VKAs. This improvement in thrombus resolution was accompanied with a better safety profile for NOAC patients vs. VKA-treated patients. Thus, provides data to support a randomized trial to answer this question.

The evolution of seeds.

The evolution of the seed represents a remarkable life-history transition for photosynthetic organisms. Here, we review the recent literature and historical understanding of how and why seeds evolved. Answering the 'how' question involves a detailed understanding of the developmental morphology and anatomy of seeds, as well as the genetic programs that determine seed size. We complement this with a special emphasis on the evolution of dormancy, the characteristic of seeds that allows for long 'distance' time travel. Answering the 'why' question involves proposed hypotheses of how natural selection has operated to favor the seed life-history phenomenon. The recent flurry of research describing the comparative biology of seeds is discussed. The review will be divided into sections dealing with: (1) the development and anatomy of seeds; (2) the endosperm; (3) dormancy; (4) early seed-like structures and the transition to seeds; and (5) the evolution of seed size (mass). In many cases, a special distinction is made between angiosperm and gymnosperm seeds. Finally, we make some recommendations for future research in seed biology.

An Observational Study Assessing Immediate Complete Versus Delayed Complete Revascularisation in Patients with Multi-Vessel Disease Undergoing Primary Percutaneous Coronary Intervention.

BACKGROUND: More than half of the patients undergoing primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) have multi-vessel coronary artery disease. This is associated with worse outcomes compared with single vessel disease. Whilst evidence now exists to support complete revascularisation for bystander disease the optimal timing is still debated. This study aimed to compare clinical outcomes in patients with STEMI and multi-vessel disease who underwent complete revascularisation as inpatients in comparison to patients who had staged PCI as early outpatients. METHODS AND RESULTS: We conducted an observational cohort study consisting of 1522 patients who underwent primary PCI with multi-vessel disease from 2012 to 2019. Exclusions included patients with cardiogenic shock and previous CABG. Patients were split into 2 groups depending on whether they had complete revascularisation performed as inpatients or as staged PCI at later outpatient dates. The primary outcome of this study was major adverse cardiac events (consisting of myocardial infarction, target vessel revascularisation and all-cause mortality).834 (54.8%) patients underwent complete inpatient revascularisation and 688 patients (45.2%) had outpatient PCI (median 43 days post discharge). Of the inpatient group, 652 patients (78.2%) underwent complete revascularisation during the index procedure whilst 182 (21.8%) patients underwent inpatient bystander PCI in a second procedure. Overall, there were no significant differences between the groups with regards to their baseline or procedural characteristics. Over the follow-up period there was no significant difference in MACE between the cohorts (P = .62), which persisted after multivariate adjustment (HR 1.21 [95% CI 0.72-1.96]). Furthermore, in propensity-matched analysis there was no significant difference in outcome between the groups (HR: 0.86 95% CI: 0.75-1.25). CONCLUSIONS: Our study demonstrated that the timing of bystander PCI after STEMI did not appear to have an effect on cardiovascular outcomes. We suggest that patients with multi-vessel disease can potentially be discharged promptly and undergo early outpatient bystander PCI. This could significantly reduce length of stay in hospital.

High Thrombus Burden in Patients With COVID-19 Presenting With ST-Segment Elevation Myocardial Infarction.

BACKGROUND: Coronavirus disease-2019 (COVID-19) is thought to predispose patients to thrombotic disease. To date there are few reports of ST-segment elevation myocardial infarction (STEMI) caused by type 1 myocardial infarction in patients with COVID-19. OBJECTIVES: The aim of this study was to describe the demographic, angiographic, and procedural characteristics alongside clinical outcomes of consecutive cases of COVID-19-positive patients with STEMI compared with COVID-19-negative patients. METHODS: This was a single-center, observational study of 115 consecutive patients admitted with confirmed STEMI treated with primary percutaneous coronary intervention at Barts Heart Centre between March 1, 2020, and May 20, 2020. RESULTS: Patients with STEMI presenting with concurrent COVID-19 infection had higher levels of troponin T and lower lymphocyte count, but elevated D-dimer and C-reactive protein. There were significantly higher rates of multivessel thrombosis, stent thrombosis, higher modified thrombus grade post first device with consequently higher use of glycoprotein IIb/IIIa inhibitors and thrombus aspiration. Myocardial blush grade and left ventricular function were significantly lower in patients with COVID-19 with STEMI. Higher doses of heparin to achieve therapeutic activated clotting times were also noted. Importantly, patients with STEMI presenting with COVID-19 infection had a longer in-patient admission and higher rates of intensive care admission. CONCLUSIONS: In patients presenting with STEMI and concurrent COVID-19 infection, there is a strong signal toward higher thrombus burden and poorer outcomes. This supports the need for establishing COVID-19 status in all STEMI cases. Further work is required to understand the mechanism of increased thrombosis and the benefit of aggressive antithrombotic therapy in selected cases.

An observational study assessing the impact of a cardiac arrest centre on patient outcomes after out-of-hospital cardiac arrest (OHCA).

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a major cause of death worldwide. Recent guidelines recommend the centralisation of OHCA services in cardiac arrest centres to improve outcomes. In 2015, two major tertiary cardiac centres in London merged to form a large dedicated tertiary cardiac centre. This study aimed to compare the short-term mortality of patients admitted with an OHCA before-and-after the merger of services had taken place and admission criteria were relaxed, which led to managing OHCA in higher volume. METHODS: We retrospectively analysed the data of OHCA patients pre- and post-merger. Baseline demographic and medical characteristics were recorded, along with factors relating to the cardiac arrest. The primary endpoint was in-hospital mortality. RESULTS: OHCA patients (N =728; 267 pre- and 461 post-merger) between 2013 and 2018 were analysed. Patients admitted pre-merger were older (65.0 vs. 62.4 years, p=0.027), otherwise there were similar baseline demographic and peri-arrest characteristics. There was a greater proportion of non-acute coronary syndrome-related OHCA admission post-merger (10.1% vs. 23.4%, p=0.0001) and a corresponding decrease in those admitted with ST-elevation myocardial infarction (80.2% vs. 57.0%, p=0.0001) and those treated with percutaneous coronary intervention (78.8% vs. 54.0%, p=0.0001). Despite this, in-hospital mortality was lower post-merger (63.7% vs. 44.3%, p=0.0001), which persisted after adjustment for demographic and arrest-related characteristics using stepwise logistic regression (p=0.036) between the groups. CONCLUSION: Despite an increase in non-acute coronary syndrome-related OHCA cases, the formation of a centralised invasive heart centre was associated with improved survival in OHCA patients. This suggests there may be a benefit of a cardiac arrest centre model of care.

Complete Versus Culprit only Revascularisation in Patients with Cardiogenic Shock Complicating Acute Myocardial Infarction: Incidence and Outcomes from the London Heart Attack Group.

BACKGROUND: Despite advances in technology, patients with Cardiogenic Shock (CS) presenting with ST-segment myocardial infarction (STEMI) still have a poor prognosis with high mortality rates. A large proportion of these patients have multi-vessel coronary artery disease, the treatment of which is still unclear. We aimed to assess the trends in management of CS patients with multi-vessel disease (MVD), particularly looking at the incidence and outcomes of complete revascularisation compared to culprit vessel only. METHODS AND RESULTS: We undertook an observational cohort study of 21,210 STEMI patients treated between 2005 and 2015 at the 8 Heart Attack Centres in London, UK. Patients' details were recorded prospectively into local databases using the British Cardiac Intervention Society (BCIS) PCI dataset. 1058 patients presented with CS and MVD. Primary outcome was all-cause mortality. Patients were followed-up for a median of 4.1 years (IQR range: 2.2-5.8 years). 497 (47.0%) patients underwent complete revascularisation during primary PCI for CS with stable rates seen over time. These patients were more likely to be male, hypertensive and more likely to have poor LV function compared to the culprit vessel intervention group. Although crude, in hospital major adverse cardiac events (MACE) rates were similar (40.8% vs. 36.0%, p = 0.558) between the two groups. Kaplan-Meier analysis demonstrated no significant differences in mortality rates between the two groups (53.8% complete revascularisation vs. 46.8% culprit vessel intervention, p = 0.252) during the follow-up period. After multivariate cox analysis (HR 0.69 95% CI (0.44-0.98)) and the use of propensity matching (HR: 0.81 95% CI: 0.62-0.97) complete revascularisation was associated with reduced mortality. A number of co-variates were included in the model, including age, gender, diabetes, hypertension, hypercholesterolaemia, previous PCI, previous MI, chronic renal failure, Anterior infarct, number of treated vessels, pre-procedure TIMI flow, procedural success and GP IIb/IIIA use. CONCLUSION: In a contemporary observational series of CS patients with MVD, complete revascularisation appears to be associated with better outcomes compared to culprit vessel only intervention. This supports on-going clinical trials in this area and provides further evidence of the association of complete revascularisation in STEMI with good outcomes.

Genome size as a predictor of guard cell length in Arabidopsis thaliana is independent of environmental conditions.

The recent discovery of a strong positive relationship between angiosperm genome size and stomatal guard cell length (GCL) opens the possibility of using plant fossil guard cell size as a proxy for changes in angiosperm genome size over periods of environmental change. The responses of GCL to environmental stimuli are currently unknown and may obscure this predictive relationship. Here, we investigated the effects of environmental variables (atmospheric CO2, drought, relative humidity, irradiance, ultraviolet radiation and pathogen attack) on GCL in the model plant Arabidopsis thaliana to quantify environmentally induced variation. GCL responded to all variables tested, but the changes incurred did not significantly impinge on the predictive capability of the relationship.